|Publication number||US7448259 B2|
|Application number||US 11/507,222|
|Publication date||Nov 11, 2008|
|Filing date||Aug 21, 2006|
|Priority date||Aug 21, 2006|
|Also published as||CA2661004A1, CA2661004C, EP2069743A2, EP2069743A4, US20080041145, WO2008024341A2, WO2008024341A3, WO2008024341A9|
|Publication number||11507222, 507222, US 7448259 B2, US 7448259B2, US-B2-7448259, US7448259 B2, US7448259B2|
|Inventors||Alan B. Cole|
|Original Assignee||Dresser-Rand Company|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (33), Classifications (15), Legal Events (3)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The present invention relates to fluid machinery such as steam turbines, and more specifically to position feedback devices for such fluid machinery.
Fluid machinery such as steam turbines are known and such turbines basically include a main casing defining a chamber, a rotatable output shaft disposed within the chamber and having at least one portion extending outwardly of the casing, and one or more rotors mounted on the shaft, each rotor having a plurality of vanes or blades. High pressure fluid is directed through one or more nozzles toward each rotor so as to cause rotation thereof to drive the output shaft, and flow through each nozzle is controlled by a valve. Preferably, such steam turbines include a steam distributor assembly or “steam chest” that includes an interior chamber fluidly coupled with a source of steam, a plurality of outlets each fluidly connected with one or more nozzles, and plurality of valves each controlling flow through a separate outlet, and thereby into each nozzle.
Particularly when the steam chest includes a plurality of valves, a valve actuator assembly is provided which includes an actuator, a cam shaft driven by the actuator and having one or more cams, and at least one follower or “lifter” each engaged with a separate one of the cams and configured to open a separate one of the valves. With such an actuator assembly, rotation of the cam shaft causes the lifters to periodically open and close each valve, so as intermittently permit flow through each nozzle to the associated rotor. As it is generally desired to control the timing of the opening and closing of the valves, previous steam turbine designs have been provided with a rotary sensor for determining the rotational movement of the cam shaft, and thereby to provide a control device with feedback information on the valve operation to ensure proper functioning thereof.
In one aspect, the present invention is an indicator device for sensing an angular position of a rotatable element of a machine. The indicator device comprises a first indicator member coupled with the rotatable element such that angular movement of the rotatable element angularly displaces the first member. A second indicator member is coupled with the first member such that the angular movement of the first member linearly displaces the second member. Further, a sensor is configured to sense at least one of linear position and linear displacement of the second indicator member so as to sense the angular position of the rotatable element.
In another aspect, the present invention is an indicator device for sensing a valve of a fluid machine, the machine including a casing having at least one interior chamber, at least one valve controlling flow into the interior chamber, and a rotatable shaft. The shaft is configured to displace the at least one valve between open and closed positions when the shaft moves between first and second angular positions. The valve indicator device comprises a first indicator member coupled with the shaft such that angular movement of the shaft angularly displaces the first member. A second indicator member is coupled with the first member such that the angular displacement of the first member linearly displaces the second member, the second member linear displacement being generally proportional to angular displacement of the first member. Further, a sensor is configured to sense at least one of linear displacement and linear position of the second indicator member so as to sense the position of the valve.
In a further aspect, the present invention is a steam turbine comprising a casing having at least one interior chamber and a valve controlling flow into the interior chamber. A rotatable shaft is mounted to the casing and configured to displace the valve between open and closed positions when the shaft moves between first and second angular positions. A pinion gear is coupled with the shaft such that angular movement of the shaft angularly displaces the pinion gear. Further, a rack gear is engaged with the pinion gear such that the angular displacement of the pinion gear linearly displaces the rack gear, the rack gear linear displacement being generally proportional to angular displacement of the pinion gear. Furthermore, a sensor is configured to sense at least one of linear displacement and linear position of the rack gear so as to sense the position of the valve.
The foregoing summary, as well as the detailed description of the preferred embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings, which are diagrammatic, embodiments that are presently preferred. It should be understood, however, that the present invention is not limited to the precise arrangements and instrumentalities shown. In the drawings:
Certain terminology is used in the following description for convenience only and is not limiting. The words “upper”, “upward”, “down” and “downward” designate directions in the drawings to which reference is made. The words “inner”, “inwardly” and “outer”, “outwardly” refer to directions toward and away from, respectively, a designated centerline or a geometric center of an element being described, the particular meaning being readily apparent from the context of the description. Further, as used herein, the word “connected” is intended to include direct connections between two members without any other members interposed therebetween and indirect connections between members in which one or more other members are interposed therebetween. The terminology includes the words specifically mentioned above, derivatives thereof, and words of similar import. Furthermore, throughout the following text, reference is made to two or more positions of various elements being described, and such positions are depicted in the drawing figures by indicating the relative positions of a single point on such elements. Such element points shown in the drawings are selected for convenience only and have no particular relevance to the present invention.
Referring now to the drawings in detail, wherein like numbers are used to indicate like elements throughout, there is shown in
More specifically, the second indicator member 14 is coupled with the first indicator member 12 such that linear displacement lD of the second member 14 is at least generally proportional to angular displacement aD of the first member 12, as indicated in
Most preferably, when the rotatable element 2 is or includes a cam shaft 3 as discussed above, the first indicator member 12 includes a “drive” pinion gear 22 coupled with the cam shaft 3, and the second member 14 includes a rack gear 24 engaged with the pinion gear 22. The cam shaft 3 has a central axis 3 a and is pivotable about the axis 3 a between a first angular position A1 (
Furthermore, the second member rack gear 24 is engaged with the pinion gear 22 such that rotation of the cam shaft 3 linearly displaces the rack gear 24 along the axis 14 a between a first position G1 (
Additionally, the sensor 16 is configured to sense when the preferred rack gear 24 is generally disposed at the first limit position G1, the second limit position G2, or/and one or more intermediate positions (none depicted) located on the axis 14 a between the two limit positions G1, G2. Preferably, the sensor 16 is configured to sense the rack gear 24 at all of the rack gear positions Gn (i.e., the limit and intermediate positions) and thereby determine when the cam shaft 3 is located at the two angular limit positions A1, A2 and at each intermediate angular position An therebetween (none depicted). Further, the control 18 is preferably configured to use such cam shaft position information to determine when the preferred valve(s) 5 are located at each “point” in a valve displacement cycle, as described in detail below. However, the sensor 16 may alternatively be configured to sense only when the rack gear 24 is located at one or more specific positions Gn, such as one or both limit positions G1, G2, such that the control 18 determines therefrom only when the one or more valves 5 are located at a particular point(s) in the valve displacement cycle, for example, the valve closed and valve fully open positions VC, VO.
More specifically, the sensor 16 preferably includes a moveable portion 26 coupled with the rack gear 24 and moveable along an axis 26 a (collinear or parallel with the rack gear axis 14 a), and a fixed portion 28 spaced from the rack gear 24 and configured to sense at least one position of the sensor moveable portion 26. Most preferably, the sensor 16 is a linear variable differential transformer or “LVDT” 30, such that the sensor moveable portion 26 includes an armature 34 with a core member 36 and the sensor fixed portion 28 includes a plurality of coils 38 (see
Alternatively, the sensor 16 may constructed so as to directly sense the rack gear 24 or an extension member (not shown) connected with the gear 24 (e.g., an elongated bar, etc.). For example, the sensor 16 may be an encoder, a proximity sensor, etc. configured to either sense displacement of the rack gear 24 or the extension member or/and to sense when the rack gear 24/extension member is located at one or more particular positions, for example by sensing when the gear/extension member is proximal to the sensor 16. Furthermore, the sensor 16 may be constructed in any other appropriate manner capable of sensing the second indicator member 12 (preferably the rack gear 24) to determine angular position of the rotatable element 2/shaft 3, and the scope of the present invention is in no manner limited to any particular structure, arrangement, operational parameter, etc. of the sensor 16.
Specifically, the rack gear 24 is disposed generally between the retainer bearing surface 44 and the two pinion gears 22, 40. As such, the rack gear 24 slides against the bearing surface 44 while the pinion gear 22 drives the rack gear 24 between the first and second linear limit positions G1, G2, the idler pinion 40 functioning to maintain the rack gear 24 disposed against the retainer 42 so as to prevent sideways movement or pivoting of the gear 24. Preferably, the retainer 42 includes a generally S-shaped (or Z-shaped) elongated plate 46, a slide member 47 mounted to a central vertical edge 46 a of the main plate 46, and a generally rectangular cover plate 48 attached to a rear vertical surface 46 b of the main plate 46. The slide member 47 provides the bearing surface 44 and is preferably formed of Teflon or a similar material. The cover plate 48 is configured to at least partially overlap the rack gear 24, such that the rack gear 24 is retained between the cover plate 48 and a base 20, as described below.
As best shown in
In other words, the cam shaft 3 rotatably drives the drive pinion gear 22 through the flexible coupler 60, regardless of whether or not the two axes 3 a, 12 a are precisely collinear so as to account for manufacturing tolerances. As best shown in
Referring now to
Referring particularly to
Referring now to
With the above structure, the sensor 16 generates and transmits the signals Sn to the control 18 when the rack gear 24 is located at each one of a plurality of the gear linear positions Gn. The control 18 is configured to sense or determine valve position Vn (i.e., VC, VO, etc.) from each rack position signal Sn and adjusts operation of the actuator 84 whenever the sensed valve position Vn varies from a desired valve position DVn stored within or inputted to the control 18. More specifically, the control 18 preferably includes at least one controller 96 that is programmed, etc., to operate the actuator 84, preferably through a relay valve 97 coupled with the cylinder 90, to periodically open and close all the valves 5 within a specified time period during turbine operation. When the control 18 determines that the valves 5 have not/are not displacing in the desired manner, the control 18 adjusts actuator operation as necessary so that the valves 5 are closed and opened at the appropriate turbine operational points and/or within the desired time period. Thus, the control 18 ensures that the valves 5 are periodically displaced between the closed and fully open positions VC, VO within the predetermined time period and at the proper operational points continuously during operation of the steam turbine 4.
It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined in the appended claims.
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|U.S. Classification||73/112.02, 73/114.26|
|Cooperative Classification||F05D2260/4031, F05D2260/53, F16K31/52408, F01D17/145, G01D5/2291, F16K37/0041, F01D17/02|
|European Classification||G01D5/22D, F16K37/00D, F16K31/524B, F01D17/14B3, F01D17/02|
|Aug 21, 2006||AS||Assignment|
Owner name: DRESSER-RAND COMPANY, NEW YORK
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:COLE, ALAN B.;REEL/FRAME:018199/0583
Effective date: 20060818
|May 11, 2012||FPAY||Fee payment|
Year of fee payment: 4
|Apr 13, 2016||FPAY||Fee payment|
Year of fee payment: 8